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DOCUMENT RESUME
ED 225 818 4, SE 040 060
AUTHOR Sharman, Ronald M.TITLE Sludge Lagoons. Sludge Treatment and Disposal Course
#166. Instructor's Guide'[and] Student Workbook.INSTITUTION Linn-Benton Community Coll., Albany, Oreg.SPONS AGENCY Office of WateF Program Operations (EPA), Cincinnati,
Ohio. National Training and Operatipmal TechnologyCenter.
PUB DATE Aug 80GRANT EPA-900953010NOTE 43p.; For related documents, see ED 224 718-720 and
SE 040 061-062.AVAILABLE FROM Linn-Bentom Community College,' 6500 SW Pacific Blvd.,
'Albany, OR 97321 ($1. student workbook, $2.instructor's guide," 1st per 6ntire set ofslide-tape, 1 student workbook and 1 instructor'sguide is $75. per unit); EPA/Instructional ResourcesCenter, 1200 Chambers Rd., 3rd Floor, Columbus, OH43212, prices from EPA are available upon request.
PUB TYPE Guides Classroom 'Use Materials (For Learner). (051) Guides Classroom Use Guides (ForTeachers) (052)
EDRS PRICE MF01 Plus Postage. PC Not Available from EDRS.DESCRIPTORS Instructional Materials; Laboratory Procedures; Post
Secondary Education; Safety; *Sludge; TeachingGuides; *Training Methods; *Waste Water; *WaterTreatment
IDENTIFIERS Sludge Lagoons
ABSTRACTThis lesson describes three different types of sludge
lagoons: (1) drying lagoons; (2) facultative lagoons; and (3)
anaerobic lagoons. Normal operating sequence and equipment.are alsodescribed. The lesson is designed to be used in sequence with thecomplete Sludge Treatment and Disposal Course #166 or as anindependent lesson. The instructor's manual contains a description of
the lesson, estiffiated presentation time,'instructional materialslist, suggested sequence of presentation, reading lists, objectiVes,lecture outline, narrative of the slide/tape program used with the
,lesson, and student worksheet (with answers). The student workbookcontains plant flow diagrams, objectives, glossary, text material,references, and workshet. Tables listing advantages/disadvantages ofusing-sludge drying lagoons and advantages/limitations of usingfacultative sludge lagoons for long-term storage are included. Safetymeasures are briefly considered. (Author/JN)
************************************************************************. Reproductions supplied by EDRS are the best that can be made *
* from the original.document... , *
i***********************************************************************
SLUDGE TREATMENT'
and
DISPOSAL
. INSTRUCTOR'S GUIDE
P repa red byLinn-Benton Community College
andEnvirotech Operating Services
r;
,
_
SLUDGE LAGOONS..
,
I.4
\
\
..,
,
r
..
Written Bye: .
Ronald M. Sharman'Linn-Benton Community College
Albany, Oregon
Iristructional Design:Priscilla HardinCorvallis, Oregon
Technical Consultant:Envirotech Operating Services
San Mateo, California
Project Director:Paul H. Mopping
Linn-Benton Community College
Albany, Oregon
-
. Project Officer:Lynn S. Marshall
Uhited States Environmental Protection Aoency
National Training and Operational TechnolOgy Center
Cihcinnati, Ohio
'Developed Under:
EPA Grant P900953010
Z... . August, 1980,
i
I
I
i
SLUDGE LAGOONS
CONTENTS
Subject . Page
Lesson Description LG-1
Estimated Time LG-1
Instructional Aids LG-1
Suggested Sequence of Presentation LG-1
Required Reading LG-1
Reference Reading LG-2
Objectives LG-3
Lecture Outline LG-4'
Narrative
' Answers to Worksheet W-LG-1
Student Materials thru 1.9
W5-LG-1 thru 3
Alt
10/82
SLUDGE LAGOONS
CtSSON DESCRIPTION
This lesson is designed to be uSed in sequence with ,61e complete
Sludge Treatment and Dispdsal Course #166, it can berused indeRendently
as a complete lesion, '
0
This lesson describes the three di.fferent,types of sludge lagoons;
drying, facultative and anaerobic lagooris-, Discussion is made of the
normal operating sequence and the equipment involved.
thIMATED
Student preview 5-10 min6tes
'Presentation 17 minutes
Discussion 10 minutes
JOorksheet . 10-15 minutes
INSTRUCTiONAL AIDS
Student text "Sludge Lagoons"
2. Slide set "Sludge Lagoons"
3. Slide projector
4, Screen-
Design drawings of lotal lagoon systems.
SUGGESTED SEQUENCE OF PRESENTATION
1, 'Assign reOing - emphasis on glossary and'objectives,
2.(
Leciure using slide. set.
3. Open disCussion.
4. Assign worksheet.
54 Correct worksheet.
' REQUTRED READING.
,-Student,text "SlUdge Lagpons"
6
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.REFERENCE READING
' (,
Process Design Manual -,Sludge Treatment an4 Disposal, pages 9-14
through 9-17, 15-22 througb 15-50.
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OBJECTIVES 4
SLUDGE LAGOONS
Upon oompletion of this lesson the student will be able to do the ,
fol
1. Explain how lagoon, as a treatnint process, fits into the Over-
,all Astewater treatment scheme.
2. 'Explain why a sludge drying lagoon resembles sludge drying beds.
3. Describe the equipment which is common to all sludge lagoon
variations.
4. List the six operating,procedures common to all types of lagoon
sys tems . -
5. Explain how the drollowing detig)a criteria affect sludge lagoon
operation:
a) Cl ima te
b) Subsojl permability,
c) Sludge characteristics
d) Depth and area,
6. Recal 1 that lagoon storage i s- not sui table for uns.tabi I i zed,
dewatered, or partially dired,sludge because of the problems. with
-septici ty.
7. Describe sludge drying lagoons.
8. Recall the sludge loading rate if' the sludge drying .lagoori-is 2.2 -
2.4 lbs/yr/ft3 of lagobn capacity.
9. Describe facultative sludge lagoons.
10. Recall that the 'Sludge loading rate of the facul tative lagoon is
20 lbs VS/1,000 ft2/day.
11. Describe anaerobic sludge lagootis.
12. ,E4lain the mechanisms of 0.2 supply in'a-facultative lagoon.
13. Explain why receiving undigested feed sludge is the major emergency
encountered during lagoon operation.
14. Recall that.lagoons are used for dewatering, further decomposition,
and storage of wastewater sludges.
15: ,Describe the general maintenanGe considerations of sludge lagoon
. ,systems .
16. Describe,the,causes of 6dor problems a1id what can be done to .solve
them.
17. Expl;aic the effeCtS'Of Poor supernatant,quality on the treatment
plant and what can be done to imprOve on .supernatant
LG-3 of 11 10/82
SLUDGE,LAGOONS
LECTURE OUTLINE
I. INTRODUCTION
A. Method of Sludge Jewatering
1. Simiiar to drying beds
Bo Drying and`deWatering accOmplished by:
1. Decanting supernatant
2: Evaporation
3. Drainage
4. Transportation
^
BASIC CONCEPT
A. Different operational variations have common design, epuipment,' and operational requirements.
B. -Design and equipment
1, Rectangular shape, retaining walls
ao Drying lagoons, 2-4 foot high
b, Anaero6ic'lagoons, 35 foot depth
. Equipment
a. Sludge feed line
b. Metering pumps '
c. Supernatant decapt lines
d. Sludge removal eouipMent
C. Operating procedures
.1. Pump Tiquid ,feed sludge'
a. Normally stabilized
2. Decant supernatant
a. toniinuously
b, Intermittently
3. rill.to desired depth and allow'to dewater
4. Remoite deWaterdd sludge
5. Resting stage
la, 3 to 6 months
6. Repeat.the cycle
LG-4 of 11 i0/82
D, Design Cri teri a_ _Cljniate
2. Subsoil permeability
3. Sludge characteristfcs
a, Anaerobicallysdigested
4, Depth and area
a. Drying lagoons 2 2-2.4 lbs/yr/ft3
b: Facultative-lagoons -.20 lfi° VS/1000 ft2.
LAGOON TYPES , -
A, SludO Drying Lagoon
1.Resemble drying beds
2, Sludge exposed to air
3. 2.2-2,4 lbs/yr/ft3
4. 24-48,inch depth
8,- Facultative Sfudge Lagoons
1. Aerobic surface area
a. Surface mixers,(brush)
b. 02atmospheric transfer
c. Cycflc - symbiotic Telationhip.
2. 20 lbs. VS/1000 ft2/day
3. Lagoon depth 11.5 - 15 ft,
C. Anaerobic Liquid Sludge Lagoons
1. Lagoon depth 15 35 ft.'
2. 5 ft. water cap
3. No surface agitatiOn
4. MAGC.
IV, OTHER OPERATIONAL CONCERNS
'A. Monitoring
1. Sensory observations
2. 'Sludge loading
_3.. Quality and characteristics
4. Depth, date, time
5. Weather
6. Supernatant quality
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13: Emergency Operating Procedures
sl, Undigested sludge
,C, Design shortcomings
1. Adverse weather
2. Small lagoon area
D. Troubleshooting,
1. Odors
, a. Insects
3. . Strong supernatant
E. MaintenanCe
1. Remove weeds ,
2. Remove supernatant
3. 'Repair dikes
F Safety
I. Gases
2. Hygiene
B
LG-6 of 11
SLUDGE LAGOONS
NARRATIVE
Slide #
1. This module discuss.es the theory, the types, and recommended operating
procedures for sludge lagoons,
2. 41e module was written by Ronald M. Sharman. instructional design wasdone by Priscilla Hardin. Paul H. Klopping was Project Director.'
3. Treatment of wastewater sludge by lagoonini,js a viable method Of sludgedewatering when sufficient, economical land is available.
4. Digested sludge lagoons were originally considered temporary sludge storagedevices. Proloned storage proved to be an effective dewatering process.
5. Sludge lagoons are Similar to sand drying beds in their modes of operation.Both operate with sludge being periodically drawn fran a digester, placedin a lagoon (or sand bed), and removed after a period of drying.
6. In lagoons, sludge oenerally requires 1 to 3 years to achieve a predeter-mined solids concentration suitable,for removal." The cycle iS then re-peated.'
-.7. There are tliree basis types or variations of sludge lagoons. Thes.e are:
1) The sludgedrying lagoon;, 2) The facultative sludge lagoon; and 3)
fhe anaerobic sludge lagoon.
8. These three variations of sludge lagoon systems contain commonidesi4M,equipment, and operational requirements.
9. 'Sludge lagoons consist of some sort of retaining walls which are normaflyearthen dikes. These vary 'from two to four feet high for drying lagoons,and up to thirty-five feet high for anaerobic sludge lagoons at the.Metropolitan-Sanitary District of Greater Chicago.
10. . The earthen dikes normally enclose rectangular basin with a permeable
bottom surface. Dikes shoulb be of a shape and size to permit maintenance,mowing, and a roadway for equipment. Lagoon width and depth are con-,
trolled by the limita 'ions of the sludge removal equipment.
11 Equipment common to ll lagoons include: 1) sludge feed lirTs and metering
pumps, 2) supernata t decant lines, and 3) some type of mechanical sludge
emoval equipment. n areas where permeable soils are uravailable,,under--d ains and associatT piping may be required.
LG-7 of 11 16/82
11.
. 12. Operating'pcocedures common to all lagoon systems involve: 1) Pumpingthe liquid sTudge and fiTlirig the lagoon to a desired depth over a periodof mcinth. The pumped sludge is normally stabilized prior to application.
,
13. 2) Depending on the climate and the depth of applied sludge, the timeinvolved for dewatering may vary. (This,may range from 1 to 3 years.)
14. 3) DecantjA- supernatant, either continuously or intermittently, from thelagoon suisface and returning it to the headworks of the wastewater treat-ment plant.
15. 4) Removing the dewatered sludge with'some type of mechanical,removalequipment with uttimate disposal as land application or landfill.
16. 5) Resting (adding np new sludge) dle lagoon for three tosix months and6) Repeating this cycle.
4
17. Proper design of ;the slu dge lagoon systeths requires close attention tothe following considerations: 1) Climate, 2), Subsoil permeability,3) Sludge characteristics, 4) Lagoon depth.
18. Proper size of the lagoon requires climatic information' concerning,: 1) ,
Precipitation rate, 2) Evaporation rate, 3) Temperature extremes. Therole of evaporation in dewatering is,especially important in the processof drying lagoons.
1. The bottom of the lagocfn should be a minimum of 18.inches above the groodwatel- table. The ,s0,,soil should have a. moderate permeability, highlypermeable sOils may reqpire-syntheEic
20. The characteristfCs of the slu dge placed in a lagoon .significantly affectodor and'Necior problems th4t can be,produced. It is recommended thatonly anaerobically digested sludge be used for lagoon applkAtions.ekerobically digested sludges have'beensused wipth some suCcess:
21. Stable liquid sludges with less than' 10% solids can be stoFid in mostlagoons. Air dried; stable sludges A greater than 30% solids can be.stored safely without odors. A
,22. Lagoon storage is not suitable for nstabilized, dewatered or partiOly .
dried sludge (fess than 30% solids ) because ofethe problems associatedwith septicit/y. ..(0dors and poor solids transport properties.)
23. The actual depth and area requirements for sludge lagoons varies depend-ing on climatic conditions, sludge type, and lagoon voluve. Wet climates
may 'require greater sludge stability and lagoon area to attain'good
dewaterability. Drier climates may be able to,handle a greater sludge
volume in a smaller lagoon area.
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24. A minimum of two separate lagoons are provided tb eiasure aVailability of.torage space durtng cleaning, maintenance, and emergency conditions,.
,,.
25. Recall that lagoons are used for dewatering, some.further,decompositiop,and storage of wastewater sludges. Let!s take a closer look at the three
different types of sludge lapoons.
LG-8 of 11 10/82
?6. Sludge drying lagooni are low cdSt; simple systems'whith closely resemblesludge drying beds because the applied sludge 'is left exposed for actual
drying ,to take place. Yrying beds can be coUrted into drying lagoonsby extending the sidem4ll depth wi.O.planking. .-
0
27. Drying lagoons have a sidewall dike height of 2 to 4 feet. Sludge is
.applied to -a depth between 2 - 3.5 feet; After decanting, *the drying
'depth averages about 15 inches.
28. Applied sludge depth can be greater in Warmer climates where the annual
rainfall is low and longer drying periods are possible.
29. Solids lpiding rates suggested for sludge'drying lagoons range between
2.2 - 2.4 lbs/yr/ft3 of lagoon capacity. After about one year of drying
. ..tIme, the sludge is dewatered from .5%,solids to about 40% solids.
30. At the end ofsthe drying cycle sludge drying'lagoons are cleaned by using
a front-end loader or other equipment whiCh can enter the lagoon to re-
move the dried sludge. The dewatered sludge can then be hkuled away .to
a final disposal site.
3 .Facultative sludge lagoons differ from sludge drying l6agoOns in that the
.
sludge isnever left exposed for actual drying to take place.. Theselagoons are designed to maintain an aerobic surface layer free of scum'
or membra'ne-film buildup.. -
32 The aerobic layer is maintained by keeping the annual organic loading
rate to the lagoon at or below 20 pounds of volatile solids per 1,000
square.feet of surface area per day and by insuring efficient 02:transfer
_at the lagoon surfae.
33. Oxygen transfer takes place naturally with the growth of photosynthetic
algae in the lagoon surface layer. Surface mixers provide agitation and
mixing of the upper layer to smpport aerobic conditions.
34. Brushmtype floating surfacemixers have been the most successful used
to provide agitation. Wixer's are most effective wtien located down-
wind where the most scum accumulates. Mixers operate 6 to 12 hours a N --day to maintain scum-free conditions.
35. As the sludge is added to this lagoon,, the digested sludge solids settle
to the bottom of the basin. Sludge liquor.or LApernatant is periodically
returned to the,plant headworks to maintain a constant liquid level.
36. Facultative fudge lagoons must operate in conjunction with anaerobic
digesters. They cannot function properly when supplied with either un-
stabilized eaerobically digested.sludge because of possible odor
problems.
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37. The practical depth'of a facultaiiye lagoon is controlled tythe limit-. ation of commercially available dredges, with the proven capacity of re-
moving solids from beneath liquid surfaces. Such equipment is capable'of remoVing sludge up to 15 feet deep.
Onder.normal operating conditions, sludge.is applied to the lagoon for _
a year, allowed to dry or concentrate for'18 mOnths,.cleaned, And, thenthe supporting material'is "rested" for six months.
39: Anaerobic sludge loons are designed for solids decomposifion'under,anaerobic conditions. Depthi of an 6aerobic lagoon can vary between15 and 35,feet. A 5,foot water cap is used to contain odors. No surfaceagitation is used in this apOlication.
40. Limited data is available for ASL hoWeVr, operationadata ftom theMetropolitan Sanitary District df Greater Chitago showed a solids loadingrate of between 36 - 50 lbs volatile solids per 1000 ft2.perChicago reports anaerobic lagoon 9ystem accomplishs an overallicvolatilesolids reduction of 17.
41. Monitoring of sludge lagoons generally consists of sensory observationsand interpretations by the plant operator. Records are kept on sludgeloading, sludge quality, weather conditions, and supernatant volume.
42 Monitoring results provides the operator with the information necessary ,
to determine the optimal time of_sludge removal from the lagoon. Keepingfi
a close eye on the supernatant quality"helps the operatOr foresee anyproblems the supernatant may cause as it is pumped back to the plant.
43. In addition to the normal filling and cleaning procedures, other oper7ational concerns include 1) Physical maintenance, 2) Water level
management, 3) Nuisance control.4
. 44. Maintenance requirements are very low for sludge lagoons. Follow man-ufacturers' recommendations for care of all mechanical equipment suchas aerators, pumping and dredging machinery. .Give regular attentiOn todike grrosion, replacement of rip-rap, and roadway condition.
45. Water level management practices vary for different lagoon systems. In
drying lagoons the operator should promptly remove supernatant liquorand rainwater to expose the Cake to the air.. In fatultative or anaerobicsystems, a constant level is maintainedsand excess supernatant is re-
6.
moved as. it accumulates.
Nuisance control is.another important operational concern. Remove weeds
and other vegetation from the lagoon area and dikes before filling with
sludge. Control offensive odors by chemical masking agents or by addingchloride of Time to the sludge .as it is discharged to the lagoon. Flies,
may be a problem in some areas and are controlled by elimation of breeding
environments and by the use of traps and poisons.
LG-10 of 11
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410., 47-)
The only emergency that may directly affect the operatipn of the sludge
lagoon anaerobic digesto upset: Undigested or poorly digestedT
sludge aplied to lagoons is likely result in odor problems.
48. Cloo't overlook safety .cofisiderat,joØ unique to lagoon operations.. Since
anaerobic digestidn of ewage sl ge produces combustible gases, smoking
or open flames should be prohibited when.discharging digested sludge to
the lagoon. Fencing and warning signs may be desirable to prevent, tres-
passing. Washing facilities should be availaio,le for both machinery and
personnel. Rrovid.e lifejackets and emergency floatation gear around
dredging anq rliaintenarice equipment.
_
,49. Sludge lagooning, whether it be drying., facultative, pr-anaerhic, is
a good mechanism for dewatering sludge. Some volatile solids-reductionis also achieved, especially in facujtastive or anaerobic systems.
- SO. Dewatering by lagooning is a very cost effective method when land is,
easily available. Lagoon operation is only,one component of the waste-
water solids treatment process and must be integrated into the overall -
wastewater treatment system.
tO,
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SLUDGE LAGOONS
WORKSHEET .Multiple Choice - Place an "X" by the best ariNer(s) or select answers as
directed in the question.
1. Sludge lagoons are another method of:
a. S.ludge conditioning
X -b. Sludge dewatering
C. Sludge inctheration
d..,&?..alige chemical treatment .
2. Lagoons (are/are not) typically provided wit[l' an undErdrain system.
a. Are
X b. Are riot
3. Before sludge is.ddded to a lagoon system, 'it should
X a.- Stabilized
b. Unstabilized
c. Heated
d. Tasted
4. 'Some Of the equipment commonly associated with sludgE lagoons includes:
X
X
a. Heat exchangers
b. Scum baffles
c. Supernatant decant lines
d. Sludge removal equipment
5. Place the following in sequential order of operation.4
Decant supernatant.
D Remove'dewatered sludge.
F' -Repeat cycle.
A Punping liquid feed sludge.
E Allow resting period.
B Fill to desired depth.
s
6. The property of soil which allows fluid to pass, with the possibility
of ground water contamihation,is called:
a.. Porosity
b. yassability"
c. Stability
X d. Permeability
W-LG-1 of 31,6
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a
7. Sludge drying lagoons have suggestqd loading rates o :
A. 1.0.- 1_9 lb./yr./ft.3
'X b. 2.2 - 2.4 lb./yrift.3
c., 2.4 - 2.7 lb./yr.:/ft.3
- 5,0 1b./yrf./ft.3,
8. 'Drying lagoons resemble sludge drying beds more Closely thanfacultative or aqerobic lagoons because:
a. They have the same dimens'ions.,
X b. Sludge is exposed t6 Air.
c. Loading rates are the'same.
d. Sludp depth is t he sa*me.
'9, Facujtative lgoons are designed to maintain a surface layer.that is:
.)( a. Aerobic
b. Anaerobic.,'
c. Absorptive , 'A
d. Alkaline
10. Along with the oxygen supplying reactipn of the cycl-ic - symbio icrelation'ship between bacteria and algae, two other mgchanism e utilizedfox-oxygen transfer. T'he two are:
a. Atmospheric transfr
b. Anabolism
c. Turbine sparging
X d. Mechanical aeration'
11. Facultative sludge lagoons A-inot function when supplied with sludgethat is:
'a. Chemically treated
X b. Aerob'ically digested
Unstabilized
. d. Anaerobically digested
ComMon depths of an anaerobic lagoon can vary between:
a. 5 - 12 feet.
X b. 15 7 35 feet.
c. 40 - 50 feet.
d. 400 - 1000.feet.
W-LG-2 of 3 10/82
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13. Anaerobic sludge lagoons are designed to operate with:
X a. A 5-foot waterrcap.
. b. Two' brush aerators.
57, volatilT soli'ds reduction.
'd. Choy6lla type algae
k
14..,Monitoring of sludge lagoons generally consists of:
a. Heavy metals analysis
.b. Color meaurements, . 4X 'c. Sensory observation.
d. TOC calculations.
15, Sludge.laAbon operational emergencies genexally consist of:
a% Dike erosion.
b. Increasing supernatant concentratiu.
c. Low solids- content.
x d, 'toss of sludge digestion process.
J6.'Sale, suggested methods for controlling orfensive odors irk ude the use of:
X a._ Chemical masking agents. .
X b. Fencing off lagoon area.
Increa&i.ng solids loading.
d, Chloride.of limrAded to the sludge feed line.]
17..What effect can the lagoon, process have on the overall wastewater"'
treatment scheme?
a. Increase costs.
b. Create dangerous operation..
c. In'enease,pH.
x d. Poor supernatant can increase loading.
18. Major safety con.siderations take into account primarily:
x a, Personal hygiene,
b. Solids concentration.
c. Access road speed,
d. Chorella,
W-LG-3 of 3
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ANI'Mk Of kW/CATION
RERMYON 10 RE PRODUCE T HIS
MAT F RIAl IN MICROFICHE ONLY
H,A, BE E N E,RANTE II BY
TO IHE Mit A H q\EAE RI MRCE
INEUEEMAIIE)N I T4 tIll 1111
4.
;a
SLUDGE LAGOONS ,
Written By:Ronald M. Sharman
Linn-Benton Community CollegeAlbany, Oregon
Ihstructional Design:Pniscilla HardinCorvallis, Oregon
Technical Consultant:Envirotech Operating Services
San Mateo,lCalifornia p; 1
Project Director:Paul H. Klopping
Linn-Benton Community College. Albany, Oregon
4
Project Officer:Lynn S. Marshall
United States Environmental Protection Agency
National Training and Operational, Technology Center
Cincinnati, Ohio
'Developed UndJr:
EPA Grant 0900953010August, 1980
-"2..t.avekt,
114.;pP
SLUDGE LAGOONS
CONfENTS
1.1
Subject Page
Plant Flow Diagrams S-LG-1
-Objectives . S-LG-2
Glossary S-LG-3
Introduction S-LG-4
Basic Concept S-Lfr-4
Lagoon 1.0`es,,,
Other Operatio0,1 Concerns S-LG-13
,
Referencp S-LG-19
Works.heet .WSLGI
.4
S-LG-i 7/82
'PRIMARY PLANT
,a+117=t;
PtANT FLOW DIAGRAMS
.",
2 114
,DIGESTER
LA6doN
SECONDARY PLANT
,
4.-1.DisposaI
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SLUDGE LAG6ONS
.
OBJECTIVES .
Upon completion of this lesson you should be able to do the
following:«
4
4.
2.
3.
e
4.
, 5
6.
a, 7.
8.
.
9:
10.
11
12
13
,
14
15.
".
Explain how lagoon, as .a treatment process, fits into the over-all wastewater treatment ,scheme.,
Explain why a sluCige drying lagoon resembles sludge drying beds.
Describe the equipment which is common to all syludge lagoonvariations. a' 4.
List the six operating proceduves common to all types of lagoOnsystems.
Explain how the following design criteria affect sludge lagoorioperation:
a). Climatet
b) Subsoil perma bi 1 i ty,
c) Sludge characterptics . .
d) Depth and area
Recall that lagoon storage is not -suitabl e for ungtabil f zed,dewatered, or partiallrdired sludge because of th,e problems with
septicity.. .
Describe sludge drying lagoons. . I
Recall the sludge lOading rate if the sludge drying lagoon is 2.2 -2.4 lbs/yr/ft3 of lagoon capacity..
..
Describe 'facultative sludge lagoons..
Recall that the sludge loading rate of the facqJ tatiye,lagoon is
20 lbs VS/1,000 ft2/day. . \.s
Describe anaerobic'ssludge lagoons. ,
Explain the mechanisms of 02 supply in a facultatiye ,l'agoon, .
Explain why receiving undigested feed sludge js the,majv emergencyencountered dur.ing lagoon operation. .
.
Recall that lagoons are used for dewatering, further decomposition,
and seorage of wastewater sludges. .
'Describe the.general maintenance konsiderations of sludge lagoon
$ systems. ,
16. Describe the causes of oddr problems and what can be done to solve,
them. .
\17. Explain the effects of poor supernatant quality on the treatnfent
plant and wNat tan be done to improve on supernatant quality.i
,
S-LG-2 of 19 "
.,
it*7/82
SLUDGE LAGOONS
' GLOSSARY
-
Aerobic - A 'condition in which "free" or dissolved oxygen is present
in the aqvati,c environment%
Anaerobic --' A condltiOn in which "free" or dissolved oxygen is not
Present in the:aquatic environment,
.Decant To pour off'without disturbing the sediment.
Dewater - To drain or remove water -rom slUdge..
Facultative - Pond:, The opper 'portion (supernatant) is aerobic,,while the Oottom layer is anaerobic.. Algae supply most of theoxygen,to the supernatant.
Penheability (1),.Jhe property of a Matbrial that permits appreciablemovement of wafer through it when it is saturated and the movementis attuated 6y Vdrostatic pressure of the magnitude normally "
encountered in the natural subsurface water. (2), The capacity of
a rock or rock.material to transmit efluid.
Septicity The condition in which organic matter decomposes to formfoulsmelling products associated with the.absence of free oxygen.
_Solids COncentrafion The amount or percehtage of.solids in'a unit
volume of water.
Stabilized Sludge A sludge that has been treated or decomposed tothe extent that, if discharged,or released, its rate alld stateof decomposition would be such that th sludge would not caus&
odors.
Supernatant Floating on surface, like oil on water.. The 14quid
overlying deposited solids. .,
. Symbiotic - The living together or close association of two dissimilar
organisms Wth mUtual benefit.
Volatile Sojids 7 Tip quantity of solids in water, sewage or sludge,lost on ignition of the dry solids at 6000 C." 2J
.
S-LG-3 of 19 7/82
SLUDGE LAa0ONS.
INTRODUCTION*dewatering method*similiar to sand drying beds
1 3 year storage v
*stabil zed sludge dnly
,BASI CONCEPTS
Sludge lagoons are another method Of sludge
dewatering when sufficient, economical land
is available. Sludge lagoons are.similar to
sand drj,ingbeds in their modes, of operation.
Both operate with sludge king periodically
drawn 'from a.digelster,.placed in a lagoon
(Or siand.be4), remoVed after a period of
drying, and the cycle is repeated, .Lagoons,
however, are not typicalII provided with an
underdrain system because most of the drying
is accomplished by decanting supernatant
liquorand by evaporation, .Also, sludge is,4
placed at depths three to four times greater
than it would be in a drying bed. And, in
fact, sOme,sludge drying beds are'temporarily
tonverted to drying lagoons by imcreasing
t the sludge depth.P o
Generally, sludge is,allowed to dewater and
dry to some predetermined solids concentra-0
tion before removal, and this may require'
one to three years, The cycle is then
repeated, Sludge Should be stabiliZed prior
to addition to the.lagoon to minimize odor
problems.
4
Different operational variations of the
treatment process of sludge lagpobing. .
-contain common design and equipment require-
ments, Sludge lagoons consist of some sort
of retaining'wall which are normally earthen
dikes, These vary from two to four feet.
high for drying lagoons to 35 feet high for
anaerobic lagoons at the (4etropolitan III
25S-1G-4 of 19 7/82
DiIesaIIow fi3r maintenance
I ,
Sanitary Distrlict of Greater Chicago (MS.DGC)
i
Prairie Plan land reclamation project'in. . .
,
Ful.ton County, Illinois: The,earthen dikes
normally enclose a r6rtangular s'pate. with./-
a permeabre surface. Dikes.ghobld be Of a ".
shape and Vze to permit maintenance, mowing,.1
\and entrwice of truc.ks and.front-end loaders.
to the lagoons-for sludge remohl:'
TquipmentAppurtenant equipment includes! sl,udge feed' .
*sludge feed lines .and metering pumps, supernatant decant
*meterslines
lines, and some type of mechanical Sludge*decant*remova uipment removal equipment. The removal equipment can .
include a bulldoz6r, drag Line or front-erid
loader, In areas where,permeable soils are
unavailable, underdraiks-and associated'
piping maj, be required
Operating procedures common to all types of
lagoon.systems involve:
1,- Pumping liquid sludge, over a period pf
several months or -more, .into the lagoon-
The pumped sludge is'Inormally stabilized
prior to application.
2 - Filling thelagoon to a desired sludge
depth and then permitting it to dewater.
Depending on the climate and the depth
of applied sludge, the time involveefor
dewatering #o a final solids content of
between 20 to 40 percent solids may be
3 to 12 months:
- 3 Decanting supernatant, either continuous-
ly or intermittentlyt from the lagoon
surface_and returning it to the headworks
of the wastewater,treatment plant,
4 .7. Removing the dewatered sludge with some
type of mechanical removal equipment.
I.S-LG-t of 19 7/82
4
PrecipitationEvaporation
- Temperature Ranges
Sludge 'Characteristic's?
4.
5 - Resting (adding.no new sludge) to the
lagoon for three to six months, ,
6 - Repeating the cycle.
Design Criteria
Proper design of sludge lagoons requires a
consideration of theipefiOing factors:
climate, subsoil permeability, sludge
c4aracteristics, lagoon depth, and area
management practices:
Climate
After dewatering by drainage and supernating,
drying in a sludge lagoon depends primarily
on evaporation, .Proper size of a lagoon,
therefore, requires climatic information
concerning:
1 Precipitation rate (annual and.selsonal).
,'2 - Evaporation rate (annual average, range, 0and seasonal fluctuations).
3 - Temperature extremes.
SubsoirPermeability
The subseil should have a moderate permea--4 -4
bility of 1.6 x 10 to 5.5 x 10 inches
per gecond, and :the bottom of the lagoon
should be a minimum of 18 inches above the
maximum ground water t'able; unless otherwise
directed by local authorities
Sludge Characteristics
The type of sludge to be placed in a lagoon
can significantly affect the amount and type
of odor and vector problems that can be
produced. It is recommended that only those
sludges which have been anaerobicalb/ digest-Ash
ed be used for lagoon applications. Stable IP
S-LG-6 of 19I .7/82
.Odor Potential!
.liquid sludge with less than 10', solids can
be stored in most lagoons, When it is air
dried to greater than 30 to 40S solids,,
'stable sludge can be StOred s'aftly.ánd witli-
out odors. It is impractitaTO store
unstabilized, dewatered or partially dried
sludge (less than 30').; solids) because
problems assOciated with Septicity (odors,
poor solids transport.properties) can
develop.
Nuisance odors will not develop in anaerobic
storage when sufficient methane bacteria are
present. If the methane bacteria.are
destroyed, however, serious odor problems
may result. As an example, consider
anaerobically digested sludge which is
placed on a drying bed or tn a drying
lagoon, The top layer of sludge is
dewatered, and methane bactergp die.as the
sludge aerates and dries.' Odor levels are
extremely low, since the sludge is too dry
to support anaerobic biological activity.
Should the surface of the sludge be rewetted4
(for example, by rainfall or surface
flooding), however, plaerobic activity would
resume, the organic acid concentration
would rapidly increase, and odors would
increase to nuisance levels. Odor problems
experienced with approximately 580 acres
of drying lagoons at San Jose, California,
immediately following a rainstorm, is a
example of this type of Problem.
Lagoon Depth and Area ,
The actual depth and area requirements
S-LG-7 of 19 '7/82
sow
,Keep surface wate,r chit
C.
Limit 'public access
LAGOON TYPES
Lagoons 3 Types*Sludge Drying*Facultative
t-- *Anaerobic
for sludge lagoons depends on several
factors such as pr4cipitation, evapOratiop,
tA/pe of sludge, volume and solids concentra
tion, Solids loading criteria have been
given as.2.2 to2,4 pounds,of solids per
year per cubic foot capacity for drying. .
lagoons to 20 pounds of yolatfle. solids per
1,000 square feet surface area for faDilta-,
tive lagoons. A mihimum of two separate
lagoons are provided to ensure availability
of storage space during cleaning, mainten-.
ance, or emergency conditions.
General Guidance
Lagoons may be of any'shape, but a rectangu-
lar shape facilitates rapid sludge removal°
Cagoo.k) dikes should have a slope of 1:3,
vertical to horizontal, and should be of a
shape and size to facilitate maintenance,
mowing, passing of maintenance vehicles
atop the dike, and access for entry of
trucks and front-end loaders into the
lagoon _Surrounding'areas should be
graded io-Trevent sUrface water from
entering the lagoon. Return must exist for
removing the surface liquid and piping to
the treatment plant.. Provisions must also
be made for limiting public access to the
sludge lagoons,
Lagoons used for dewaterimg, some decoMposi-
tion, and storage of waStewater sludges are
classified into three areas:
Sludge Drying Lagoons
Facultative Sludge Lagoons
Anaerobic Sludge Lagoons
S-LG-8 of 19 7/82
Nt.
Drying Time*2-3 years
SlUdge Drying Lagoons
Lagoon drying is a low-cost, simple system
for sludge dewatering that is commonly used
in the United States, Drying lagoons resemble,
sludge drying beds more closely than the other
two lagoon systems because the applied sludge
is left exposed for actual drying to take
place.
Sol ids loading rates .sugges ted for dryi ng
lagoons are.,2,2 to 2!4 lb /yr /cu ft of
lagdon capacity Other designers have made
recommendations ranging from 1 sq,, ft,/capita
for primary;digested sludges in an arid
climate to as high as 3 to 4'sq. ft,/capita
for activated sludge plants where the
annual rainfall is 36 inches, A dike height
of about 2 'feet with the depth of applied
sludge between 24 to 48 inches and the depth
of sludge after decanting of 15 inches has
been used ludge depths of 2 5 to 4 feet
may be used i\n warmer climates where longer
drying periods are possible Sludge may be .
deWatered from 5% solids to 40 to 45% solids
in 2 to 3 years, using sludge depths of 2 to°
4 feei.
ADVANTAGES AND DISADVANTAGES OF USING SLUDGE DRYING LAGOONS
Advantages Disadvantages
Lagoons are low energY consumersLagoons consume no chemicals -
Lagoons are not sensitive to sludgevariability
The goons.can serve as a buffer in thee handling flow stream. Shockngs due to treatment plant upsets
ca. be discharged to the lagoons withmin mal impact
Orga ic matter is further stabilizedOf all the dewaterin;i systems available,
lagoons require the least amount ofoperation attention and skill
.
It land isjivailable, lagoons have a verylow capital cost
Lagoons may be a source of periodic odorproblems, and these odors may be difficuleto control
There is a potential for pollution ofgroundwater or nearby surface water
LagoOns can create vector problems (forexample, flies and mosquitos)
La000ns are mure visible to the general
Lagoons are mote land-intensive than fullymechanical methods
Rational engineering design data arcslacking to allow sound engineeriTrgeconomic analysis
S-LG-9 of 19 7/82
Aerobic Surface*mixers help*Algae
AN,
Facultative Sludge Lagoons
Facultative. Sludge Lagoons (FSL's) are designed .
to maintain an aerobic sUrface layer free of
sdum or membrane-type film build-4p. The
aerobic layer is maintained by keeping the
annual organic loading to the lagoon at or
below a critical area lodding rate of 20
pounds of volatile solids pei- 1,000 square
feet per day and by using surface mixers to
provide agitation and mixing of the aerobic
surface layer. For example, FSL's with
surface areas of from 4 to 7 acres require
the operation of two surfacebixers from 6
to 12 hours Per day to successfully maintain
scum-free surface conditions. All of the
successful.installations, to date, have used
brus-h-type floating surface mixers to
achieve,the necessary surface agitation., Thell,
aerobic surface layer of the FSL's is
usually from one to three feet in depth and
supports.a very dense population of between
50 x 103
and 6 x 106organisms/ml of algae
(Chorella) Dissolved oxygen is supplied to
this layer by algal photosynthesis, by
direct surface transfer from the atmosphere,
and by the surface mixers ,The oxygen is
used by the bacteria in the aerobic degrad-
ation of colloidal and soluble organic 4tter
in the digested sludge liquor, while the
digested sludge solids settle to tile bottom
of the basins and continue their anaerobi'd
decomposition Sludge qjquor or supernatant,
-is periodically returned to the plant's
liquid process stream,
e .3
S-LG-10 of 1gv,.
7/82
4
Algae*symbiotic relatipnship*prevents odors
Facultative Sludge Lagoons*require anaerobic digesters
*dredge for solids removal
The nutrient and carbon dioxide released in -
both the aerobic and anaerobic degradation
of the remaining organic matter within the
digested sludge are, in turn, used by,the
algae in the cyclic-symbiotic relationship, -
This vigorous 'relationship maintains the pH
of the FSL surface layer between 7,5 and 8,5,
which effectively minimizes an'y hydrogen
sulfide (H25) release and is believed to
be one of the major keys to the successful.
operation of this sludge storage pucess.
Facultative sludge lagoons must operate in
conjunction with anaerobic digesters, They
cannot function properly when s.upplied, with .
either unstabilized or aerobically digested
sludge. If the acid phase of anaeribic
stabilization becomes predominant, the lagoons
will produce odors.
FSL depth was established by the practical,
limitation of commercially available dredges
with a proven capability of r:emoving raste
water solids from beneath liquid surfaces
Equipment that meets this requirement is
available to extract sludge from FSLs up to
11,5 and 15 feet
S-LG-11. of 19 7/82
SUPERNATANTOVERFLOW
AUTOMATICCONTROL VALVE
PREVAILING wIND DIRECTION/
'41..41- SLUDGE REMOVAL tp A 2VALVES
SURFACE MIXER
TYP,I CAL .FSL LAYOUT
Water- Cap*prevents odors
r
774'
DIGESTED SLUDGELINE ---
DIGESTED SLUDGE /INLETS
SURF MIXER ---
AnaerobiC Liquid Sludge Lagoons
Anaerobic sludge lagoons are designed, for
decomposition under anaerobic conditions
Depths of an anaerobic,lagoon can vary between
15'to 35 feet Anaerobic decomposition takes
place in varying sludge layers utilizing at ,
least a 5-foot water cap tocontain odors.
No surface agitation is used in this
application.
SLUDGEREMOVAL
t \DREDGEANCHORPOSTS(TYP)BOTH,
, ENDS
7
Operational data from the Metropolitan Sanitary?,
District of Greater Crcago's Prairie plan
Land Reclamation Project indicates a feed
sludge of 57% volatile solids which is loaded
to different lagoons at rates of 36,t9 50
pounds volattle solids per. 1000 sq. ft. per
day These anaerobic lagoon systems accom-.
plish an overall volatile solids reduction oil17 percent,
)
S-LG-12 of 19.10
7/82
a..
OTHE'R OPERATIONAL CONCERNS
Monitoring:loading*sludge quality*characteristics*depth.*date*time*weather
-*supernatant
In this...,operatillon the lagoon supernatant is
'di-i-pased of 'on 1,320 aares,of'alfalfa=brome
hay fields. Average annual, quantity,to dis-
pose equals 700,000 wet tons with an average,
ammonia content of 1099 mg/1 and an average
TKN content ,of 156.4 mg/l.
Monitoring
Monitoring of sludge lagpons generally°pn-
' sists of sensory observations and interpreta-
tions by the plant operator. However, records
\ may be kept on the sludge loading, slydge
quality and-characteristics, de6th, tiaek,
time, weather conditions, supernatant wfume,
and quality. ThiS will provide the operator
with-thp information necessary to determine
the optimal time of sludge removal ;from the
lagoon. Keeping a closeteye on the super-,
natant quality wil+help the operator foresee
any problems the supernataat may cause as it
is pumped back to the plant.
Emergency Operating Procedures
The only emergency that may directly affect'
the operation of the sludge,lagoon is the
loss af the sludge digestion.process. Undi-
gested or poorly digested sludge applied to
lagoons is likely to result in an odor
proBlem and should be avoided.
Design Shortcomings
Adverse weather conditions may Prolong the
drying of sludge, however., short rainy periods
'S-L6:13 of 1, 7/82
folTowed by sunny.conditions should 'pose no.
problemS. Problems of too little lagoon
area may be minimizediby always removing the
sludge when it is dry enough and removing
supernatant as:it forms
Maintenance Considerations_
Low AAaintenance Maintenance requirements are very lo, Or
sludge lagoons '4eeds and -Oh-2 voetati,in
should always tq. req..ved r aro.A
'before filling witn sludge l'trt Upt-rator
should pro.,ip,ly ,T,rnatunt liqUor
and rain sv u ludge cake is
expoled to 'h dnd div:
rapid1 )'1!i lntacoltati\,.-
wr.aliat:ropic syst.ems, a Loostant level CS
Mai,,itained and ecess supernatant is cedluvt:d
t'.) it accumulates
Odor Control*Masking agents*Lhne
A
.`
A--Repairing of broken dikes and water from
4
rainfall or snow require minimal operator
time
Troubleshooting.
Odor Problems,
Two basic approaches are available to control
or counteract odors: chemicals spred into
the atmosphere or chemicals added to the
sludge. Chemicals are avdflable'Aich may
be spr:ayed into the atmosphere in the.vicinity
. of the odor to counteract or.mask the odors,
Odors uey also, be.controlled effectively by
adding chloride of-lime to,the slOdge as it
is discharged to &ludge drying lagoons
S-LG-14 of 19 7/82
Fly Control*traps and poison*borax*calcium'borate*chloride of lime*sulfate of iron
Poor Super'natant*B roken di kes*Early drawdown*ExcessiVe sludge depth
Odors can also be caused by a loss or decrease
in 'aeration potentia) of facdlt'ative lagoons
or by a too shallow water cap in anae obic
systems,
Flies may be a problem in certain areas and
seasons and shouldbe controlled by destruc-
tion, of breeding and use of trips and poisons.
The fly may be controlled most effectiyely in
the larva, stage and borax or calcium borate
wfll kill, the larva. Neither chemical is
dangerous to man nor domestic animals. Other
chemjcals sometimes,used are. chJoride of lime
and sulfate of iron. The adult fly 'can be
killed by spraying.
In onsidering the sludge lagoon as part of
the overall process of wastewater treatment,
we can see the possible effects the lagoon
may have on the rest of the system. Super-.
natant decanted trom the lagoon can ppset the
treatrient process when' it is recycled. Some
. causes Of degraded supdrnatant include:
1 -' Broken dikes between lagoons allowing for
frdsh feeesludge to mix with supernatant.
2 -' Supernatant being drawn down prema-turely,
; 3 Excess i ve sl udge depths appl led causi ng
upernatant,draw off to be below the sludge .
'interface.
Problems of degraded supernatant quality can
be'isolved by a good.strategy of operation and
a program of supernatant monitoring.
S LG-15 of 19 7/82
Safety*No Smoking*Fencing*Hygiene Facilities
4
1
%
Safety Considerations. 4
4.
Since anaerobic digestion of,gewage sludge'
produces combustibfe.gases, smOking 'or open
fires should be prohibited leen discharging
anadfobically digested sludge'to!the lagom
Fencing of lagoons may be d.tsirable to'pre- -
vent trespassing, Washing-facilities srould
'be'available for'both.machinery and personnel
Pers'onal hygiene must be of concern because
of the nature of the material being treated,
Costs
Cost information on capital cost of construc-
tion of sludge lagoons fs almost nonexistent
Labor requirements for sludge dry lagoons are
covered in the following,table. The require-
ments include: application of sludge td the
lagoon; periodic reMoval supernatant;
periodic removal of solids; and minor main-,
tenance requirements.
The major elements involved ln determining
facultative sludge lagooncosts at2e land and, '
earth moving, both are quite sitéspecific-,,
For example, a typical FSL s'torage facility
for a 10 MGD secondary activated sludge
treatment plant with primary stclimenAation,
anaerobic digestion, and normal s:trength
domestic and industrial sewage will cost'about
$25,000 per year to operate (1978 dollars). ,
Some of these operational costs being used to
supply energy to the surface aerators. Addi-411
tion of a dredge and/or booster pump wouldA
S-LG-16 of 19A.c .
7/82
r
ADVANTAGES:AND LIMI*TIONS OF USING FACULTATIVE SLUDGE',LAGOONS FOR LONG-TERM STORAGE . 1/4
. ,
,dvantageL* 1.,mitations
Provides long-tetm storage Withacceptable envxronmental'tmpacts(odor and groundwater contaminationrisks are minimized)..
continues anaerobic stabilization, with upto 45 percent VS reduction p..n first year.
leecanting ability,assures minimuM solidsrecycle with, supe'rnatant (usually lessthan 500 mg/1) arid maximum concentrationfor storage and a!ffIcient harvesting('6 percent solids) starting with digestedsludge of c2 pergent
4400tbng-term liquid sorage is one of fewnatural ,(neezctexnal.energy input) meansof reducing pattfogep:content of sludges.
Energy 'and opera0onft,1 , effort requirement:,are very minim*. ,
Once establishedd buffet'ing capacity isalmOst impos'sible to upset.
Allows for all tributari digesters tooperate as primary'coalplete-mix units(one blending unit:may be required forlarge installations).
,
Provides environmentally cceptable placefor dispos1 of digeste contents duringperiodic cleaning operations.
Sludge harvesting s completely independentfrom sludoe production.
-1f.
TYPICAL FSL CROSS SECTION
3'0" AEROBIC LAYER
120" ANAEROBIC) LAYER
INGESTED SLUDGE?INLET
1 ft = 0.36in I. 2 5 cm
't 't*-1
6-IMPERVIOUS,LAYER
.k4
!JOT TO SCALE
1 . Can only be' used following anaerobicstabilization. If acid phase of,digestion t,3Xes place in lagoons they'wtll
2. Large acreages require special odormitigation measures.
3. Requites large areas of land, for.example, 15 to 20 gross acres (6
8 ha) for 10 MGD, (438 l/s) 200gross acres (80 ha) for 136 MGD(6,000 1) carbonaceous activatedsludge plants:
4. Must be protected from flooding.
to
5. Supernatant will contain 300-600 mg/1of TKN, mostly ammonia.
6: Magnesium ammonia phosphate (struV'ite)deposition reguiresspecial supernat-
v
ant design.
SLOPE 3
Fe 25 ft
FREEBOARD .---72,4,/,2,313":RIP RAP SLOPE/, 4 /iPROTECTION,
Li/ ,Z/_,ENGIIVECRED FILC8" DIGESTEDSLUDGE UNE
MINIMUM NATURAL"213-COVER GRADE
S-LG-17 of 19 7/82
4
Lagoon*Dewatering,ACost Effective
add another $150,000 to $180,000 to the con-
struction Ccitts;
Sludge lagooning, whether it be drying, facu'l-
tative, or anaerobic, is a good mechanism for
dewatering sludge. Dewatering is the removal
of water from wastewater treatment plant
solids to achieve a volume reduction. Some
volatile solid reduction is also achieved,
especial ly in facul tative .or ariaerobic
systems Dewatering by lagooning is a very
cost effective method, when land is easily
available It is done primarily to decrease
the capital, and operating costs of direct
sludge,disposal or conversion. Dewatering
sludge from a 5 to .29percent solids con-, -\
c6tration reOuces,-4lume by three-fourths
and resu 1 ts in 'a non-fluid material . Dewater-Ah
ing is only one \c\o\mponent of the wastewater II/solids treatment proc'ess and.must be integrated
into the overall wa\tewater tieatment system
so that performanee both the liquid and
solids treatment schem s is optimized and,
total costs are minimize
At
AO-
SLUDGE LAGOONS
References
1, ProCess Design Manual for Midge Treatment and Disposal, USEPA,EPA 430/9-78-011; Cincinnati, 1979.
2. Operations Manual for Sludge Handlihg;and Conditioning, USEPA,
EPA 430/9-78-002, February, 1978.
3. WPCF Manual of Practice No. 20,- Chapter-3., Sludge DewaIering.
4. Lab-oratory Study of Dewatering Rates for Digested Sludge in Lagoons,Jeffrey, E. A., Proceedings of 14th Purdue Industrial Waste Confer-,
ence. Purdue University, Lafayette, Indiana 47907 1956,
5. Dewaterinq Rates for Digested Sludge in' Lagoons; Jeffrex,.E. A.,
Journal Water Pollution Control Federation. Volume 32, p. 1153,
1960.
Fel()
S-LG-19 of 19 7/82
1
4
SLUDGE LAGOONS
WORKSHEET
Multiple Choice .7. Place an " " by the'best answer(s) or select answers as
directed in the question.
1. Sludge lagoons are another method of:
sa. Sludge conditioning'
.b. Sludge dewatering
c. Sludge incineration
d. Sludge chemical treatment
2. Lagoons (are/are not) typically provided with an, underdrain systerh.
Are
b. Are not
3. Before sludge is added to a lagoon system, it should be:.
a. Stabilqed
b. Unstabilized
C. Heated
d.,1 Tasted
4. !Some of the'equipment commonly associated with sludge lagoons includes:'
a. Heat exchangers
b. Scum baffles'
c. Subernatant decant lines
d., Sludge removal'equipment
5. Place the Following in sequential .O,der of operation.
Decant supernatant.
Remove dewatered sludge.
Repeat cycle.
Punping li9uid feed slud
.Allow resting period.
Fill to desired depth.
e.
6. The property of soil which dllows fluid to pass, with the possibility
of ground water contamination,is called:
a. PorOsityk
b. Passdbility
c. Stability
d, Permeability
.WS-LG-1 of 3 7/82
7. Sludge drying lagoons have suggested loadiDg rates of:
a. 1.0 - 1,9 lb./yr./ft.3
- 2.4 lb./yraft.3
- 2.7 lb.tyr./f.3
d. 3.0 - 5.0 lb./yr./ft.3
8. Drying lagoons resemble sludge drying beds more closely thanfacultative or anaerobic lagoonsbecause:
a. They have the same diMensiqns.
b. Sludge is exposed to air.
c. Loading rates are the saMe.
d. Sludge depth is the same.
9. Facultative lagoons are tesigned to maintain a surf,lce layer that,is:
a. Aerobic
b. Anaerobic
c. Absorptive
d. Alkaline
10. Along with the oxygen supplying reaction of the cyclic - syMbioticrelationship between bacteria and algae, two other mechanisms are utilized
for oxygen transfer. The two are:
a. Atmospheric transfer
b. Anabolism
c. ,Turbine marging
d. Mechanical aeration
11. Facultative sludge lagoons cannot function when supplied with sludge
that
a. Chemically treated-
b.' AerobicallY,digested
c. Unstabilized
d.. Anaerobically digested
12: Common depths of an anaerobic lagoon can vary between:
a. 5.- 12 feet.
b. 15. 1 35 feet.
c. 40 - 50 feet.
d. 400 - 1000 feet.
WS-Mr2 of 3 7/82
1
13. Anaerobic sludge lagoons are designed to operate with:
a. A 5-foot water cap.
b. Two brush aerators.
c. 57',:; volatile solids reduction,,
d. Chorella type algae'
14. Monitoring of sludge lagoons generally consists of:
. a. Heavy metals analysis
b. Color measurements,
c. Sensory observation.
d. TOC calculations.
15, Sludge lagoon operational emergencies generally consist of:
a. Dike erosion.
b. Inc.reasing supernatant concentration.
c. Low solids content.
d. "loss of sludge digestion process.
16. Some suggested methods for controlling offensfve odors intlude the use Of:
a Chemical masking agents.
b. Fencing off lagoon area.
c, Increasing solids loading.
d Chloride of lime added to the sludge feed line.
17. What effect can the lagoon process have on the overall wastewater$
treatment scheme? '
a. 4ncrease costs.
b. ,Create dangerouS operation.
c Increase pH.
d. Poor supernatant can increase loading.
18. Major safety considerations take into account primarily:
a, Personal hygiene.
Solids concentration.
c. Access road speed.
d. Chorelia,
4 t`
WS-LG-3 of 3 7/82